/Engine/Plugins/Online/OnlineSubsystem/Source/Public/OnlineNotificationHandler.h
This class is a static manager used to track notification transports and map the delivered notifications to subscribed notification handlers
class FOnlineNotificationHandler
TMap<FString, ...
PlayerBindingMap
Map from player and type of notification to the delegate to call
NotificationTyp...
SystemBindingMap
Map from type of notification to the delegate to call